gconf is not supported by any interfaces. gconf is an antiquated technology that has been replaced by gsettings. I suggest that your application be adjusted to use gsettings instead (I am unfamiliar with the musicbrainz code, but I suspect that this application already will try to use gsettings and is simply setting gconf to try to cover all the bases, so this may actually be either a non-fatal error or it can by made non-fatal through a minimal code change).